The production of a highly integrated semiconductor element generally has a series of processes as follows: a conductive thin film such as a metal film as a conductive wiring material and an interlayer dielectric film for insulation between conductive thin films are formed on an element such as a silicon wafer; after that, a photoresist is uniformly applied to the surface thereof to provide a photosensitive layer, and this is subjected to the selective exposure/development treatment to form a desired photoresist pattern; then the dry etching treatment is applied to the interlayer dielectric film using the photoresist pattern as a mask to form a desired pattern on the thin film; and then the photoresist pattern, residue generated by the dry etching treatment (hereinafter referred to as “dry etching residue”), etc. are completely removed by ashing with oxygen plasma, cleaning with a cleaning solution or the like.
Recently, the miniaturization of design rules has been accelerated, and the limit of high-speed arithmetic processing has been gradually controlled by signal transmission delay. For this reason, the conductive wiring material has been changed from aluminium to copper which has lower electrical resistance, and the interlayer dielectric film has been changed from a silicone oxide film to a low dielectric constant film (a film having a dielectric constant of less than 3, hereinafter referred to as “low-k film”). Patterns of 0.2 μm or less have problems in which, for example, the aspect ratio of a pattern of a photoresist having a film thickness of 1 μm (the ratio obtained by dividing the film thickness of the photoresist by the line width of the photoresist) is too large, resulting in collapse of the pattern. In order to solve this, sometimes used is the hard mask method in which: a titanium-based or silicon-based film (hereinafter referred to as “the hard mask”) is inserted between a pattern film on which a pattern is desired to be actually formed and a photoresist film; a photoresist pattern is transferred to the hard mask by dry etching; and after that, this hard mask is used as an etching mask to transfer the pattern to the film on which the pattern is desired to be actually formed by dry etching. In this method, a gas to be used for etching the film on which the pattern is desired to be actually formed may be changed from a gas to be used for etching the hard mask. It is possible to select a gas which can secure a selection ratio with the photoresist when etching the hard mask and to select a gas which can secure a selection ratio with the hard mask when etching the actual film. For this reason, there is an advantage that a pattern can be formed with a thin photoresist. Further, a tungsten-containing material is used for a contact plug for connection to a substrate.
With the miniaturization of design rules, thinning of the gate insulating film of the transistor has been approaching the limit, and a high dielectric constant film has been gradually used for the gate insulating film. Since it is difficult to control the threshold voltage by a polycrystalline silicon which is conventionally used for the high dielectric constant film as the gate material, a material containing titanium or tungsten is sometimes used as the high dielectric constant film. Further, in aluminium wirings, a tungsten-containing material is used for a contact plug which connects wirings of different layers.
Since a hard mask, a low-k film, a tungsten-containing material and copper or a copper alloy are exposed in the process of removing a dry etching residue and a photoresist in this way, when a dry etching residue and a photoresist are removed with oxygen plasma, the hard mask, the low-k film, the tungsten-containing material and the copper or copper alloy are damaged due to exposure to oxygen plasma or the like, resulting in significant deterioration of electrical characteristics and problems in production processes after that. For this reason, it is desired to suppress damage to these materials while removing the dry etching residue and the photoresist at a level comparable to that of an oxygen plasma process.
Regarding the treatment with a cleaning solution, it is known that a dry etching residue and a photoresist can be removed by using a strong alkali-based cleaning solution or an oxidant-containing cleaning solution. The strong alkali-based cleaning solution may remove a residue, but its removability of the dry etching residue and the photoresist is inferior to that of the oxidant-containing cleaning solution. Meanwhile, the oxidant-containing cleaning solution has excellent removability of the dry etching residue and the photoresist, but when it is brought into contact with a material containing titanium or tungsten, the material containing titanium or tungsten is significantly damaged. For this reason, it is desired to develop a cleaning solution containing an oxidant capable of effectively removing a dry etching residue and a photoresist without damage to a titanium-containing material or tungsten-containing material. In addition, it is desired to develop a cleaning solution containing an oxidant which does not damage copper or a copper alloy as well as a material containing titanium or tungsten.
Patent Document 1 proposes a wiring forming method using a cleaning solution containing an oxidant, quaternary ammonium hydroxide, alkanolamine, alkali metal hydroxide and water. When using this cleaning solution, it is possible to remove a residue while suppressing damage to a low-k film, but damage to a titanium-containing material cannot be suppressed. Accordingly, this cleaning solution cannot be used for cleaning a semiconductor element, wherein damage to a titanium-containing material and a low-k film is suppressed and a dry etching residue is removed, which is the purpose of the present invention (see Comparative Examples 19 and 20).
Patent Document 2 proposes a wiring forming method using a cleaning solution containing an oxidant, a metal etching agent and a surfactant and having a pH value of 10 to 14. When using this cleaning solution, it is possible to remove a residue while suppressing damage to a low-k film, but damage to a titanium-containing material cannot be suppressed. Accordingly, this cleaning solution cannot be used for cleaning a semiconductor element, wherein damage to a titanium-containing material and a low-k film is suppressed and a dry etching residue is removed, which is the purpose of the present invention (see Comparative Examples 21 and 22).
Patent Document 3 proposes a wiring forming method using a cleaning solution containing a cleaning agent, a basic organic compound, an acidic organic compound, an imidazole and water. When using this cleaning solution, it is possible to suppress damage to a titanium-containing material, but a residue cannot be removed, and damage to a low-k film cannot be suppressed. Accordingly, this cleaning solution cannot be used for cleaning a semiconductor element, wherein damage to a titanium-containing material and a low-k film is suppressed and a dry etching residue is removed, which is the purpose of the present invention (see Comparative Example 23).
Patent Document 4 proposes a wiring forming method using a cleaning solution containing a cleaning agent, a basic organic compound, an acidic organic compound, a nitrogen-containing non-aromatic cyclic compound and water. When using this cleaning solution, it is possible to suppress damage to a titanium-containing material, but a residue cannot be removed, and damage to a low-k film cannot be suppressed. Accordingly, this cleaning solution cannot be used for cleaning a semiconductor element, wherein damage to a titanium-containing material and a low-k film is suppressed and a dry etching residue is removed, which is the purpose of the present invention (see Comparative Example 24).
Patent Document 5 proposes a wiring forming method using a cleaning solution containing a hydroxylamine-based compound, amine, a water-soluble organic solvent, a metal anticorrosive and water. When using this cleaning solution, it is possible to suppress damage to a titanium-containing material, but a residue cannot be removed, and damage to a low-k film cannot be suppressed. Accordingly, this cleaning solution cannot be used for cleaning a semiconductor element, wherein damage to a titanium-containing material and a low-k film is suppressed and a dry etching residue is removed, which is the purpose of the present invention (see Comparative Example 25).
Patent Document 6 proposes a wiring forming method using a cleaning solution containing phosphoric acid, hydrochloric acid, amine, an alanine type surfactant and water. When using this cleaning solution, it is possible to suppress damage to a tungsten-containing material, but a residue cannot be removed, and damage to a low-k film cannot be suppressed. Accordingly, this cleaning solution cannot be used for cleaning a semiconductor element, wherein damage to a tungsten-containing material and a low-k film is suppressed and a dry etching residue is removed, which is the purpose of the present invention (see Comparative Example 26).
Patent Document 7 proposes a wiring forming method using a cleaning solution containing hydrogen peroxide, a triazole and water. When using this cleaning solution, it is possible to suppress damage to a low-k film while removing a residue, but damage to a tungsten-containing material cannot be suppressed. Accordingly, this cleaning solution cannot be used for cleaning a semiconductor element, wherein damage to a tungsten-containing material and a low-k film is suppressed and a dry etching residue is removed, which is the purpose of the present invention (see Comparative Examples 27 and 28).
Patent Document 8 proposes a wiring forming method using a cleaning solution containing hydrogen peroxide, quaternary ammonium hydroxide, quaternary ammonium salt and water. When using this cleaning solution, it is possible to suppress damage to a low-k film while removing a residue, but damage to a tungsten-containing material cannot be suppressed. Accordingly, this cleaning solution cannot be used for cleaning a semiconductor element, wherein damage to a tungsten-containing material and a low-k film is suppressed and a dry etching residue is removed, which is the purpose of the present invention (see Comparative Examples 29 and 30).
Patent Document 9 proposes a wiring forming method using a cleaning solution containing an inorganic base, quaternary ammonium hydroxide, an organic solvent, azole and water. When using this cleaning solution, it is possible to suppress damage to a tungsten-containing material, but a residue cannot be removed, and damage to a low-k film cannot be suppressed. Accordingly, this cleaning solution cannot be used for cleaning a semiconductor element, wherein damage to a tungsten-containing material and a low-k film is suppressed and a dry etching residue is removed, which is the purpose of the present invention (see Comparative Example 31).
Patent Document 10 proposes a wiring forming method using a cleaning solution containing hydrogen peroxide, hydrofluoric acid, an organic solvent, azole and water. When using this cleaning solution, it is possible to remove a residue, but damage to a tungsten-containing material and a low-k film cannot be suppressed. Accordingly, this cleaning solution cannot be used for cleaning a semiconductor element, wherein damage to a tungsten-containing material and a low-k film is suppressed and a dry etching residue is removed, which is the purpose of the present invention (see Comparative Examples 32 and 33).
Patent Document 11 proposes a wiring forming method using a cleaning solution containing hydrofluoric acid, an organic solvent, azole and water. When using this cleaning solution, it is possible to suppress damage to a tungsten-containing material, but a residue cannot be removed, and damage to a low-k film cannot be suppressed. Accordingly, this cleaning solution cannot be used for cleaning a semiconductor element, wherein damage to a tungsten-containing material and a low-k film is suppressed and a dry etching residue is removed, which is the purpose of the present invention (see Comparative Example 34).
Patent Document 12 proposes a wiring forming method using a cleaning solution containing hydrofluoric acid, a silicon-containing compound, a surfactant, carboxylic acid, an anticorrosive and water. When using this cleaning solution, it is possible to suppress damage to a tungsten-containing material, but a residue cannot be removed, and damage to a low-k film cannot be suppressed. Accordingly, this cleaning solution cannot be used for cleaning a semiconductor element, wherein damage to a tungsten-containing material and a low-k film is suppressed and a dry etching residue is removed, which is the purpose of the present invention (see Comparative Example 35).
Patent Document 13 proposes a wiring forming method using a cleaning solution containing a sugar, a hydroxylamine, a quaternary ammonium compound, an organic acid and water. When using this cleaning solution, it is possible to suppress damage to a low-k film, but a residue cannot be removed, and damage to a tungsten-containing material cannot be suppressed. Accordingly, this cleaning solution cannot be used for cleaning a semiconductor element, wherein damage to a tungsten-containing material and a low-k film is suppressed and a dry etching residue is removed, which is the purpose of the present invention (see Comparative Example 36).
Patent Documents 14 and 15 propose a wiring forming method using a cleaning solution containing an acid or salt thereof, a chelating agent containing nitrogen atoms, an organic solvent and water. When using this cleaning solution, it is possible to suppress damage to a tungsten-containing material, but a residue cannot be removed, and damage to a low-k film cannot be suppressed. Accordingly, this cleaning solution cannot be used for cleaning a semiconductor element, wherein damage to a tungsten-containing material and a low-k film is suppressed and a dry etching residue is removed, which is the purpose of the present invention (see Comparative Example 37).
Patent Document 16 proposes a wiring forming method using a cleaning solution containing N,N-diethylhydroxylamine, hydroxylamine, a water-soluble organic solvent, a metal anticorrosive and water. When using this cleaning solution, it is possible to suppress damage to a tungsten-containing material, but a residue cannot be removed, and damage to copper or a copper alloy, a low-k film and a titanium-containing material cannot be suppressed. Accordingly, this cleaning solution cannot be used for cleaning a semiconductor element, wherein: damage to a titanium-containing material and a low-k film is suppressed and a dry etching residue is removed; damage to a tungsten-containing material and a low-k film is suppressed and a dry etching residue is removed; or damage to a titanium-containing material, a tungsten-containing material, copper or a copper alloy and a low-k film is suppressed and a dry etching residue is removed, which is the purpose of the present invention (see Comparative Example 39).
Patent Document 17 proposes a wiring forming method using a cleaning solution containing alkanolamine, N,N-diethylhydroxylamine, diethylene glycol monoalkyl ether, a sugar and water. When using this cleaning solution, it is possible to suppress damage to a tungsten-containing material, copper or a copper alloy and a titanium-containing material, but a residue cannot be removed, and damage to a low-k film cannot be suppressed. Accordingly, this cleaning solution cannot be used for cleaning a semiconductor element, wherein: damage to a titanium-containing material and a low-k film is suppressed and a dry etching residue is removed; damage to a tungsten-containing material and a low-k film is suppressed and a dry etching residue is removed; or damage to a titanium-containing material, a tungsten-containing material, copper or a copper alloy and a low-k film is suppressed and a dry etching residue is removed, which is the purpose of the present invention (see Comparative Example 40).
Patent Document 18 proposes a wiring forming method using a cleaning solution containing potassium hydroxide, quaternary ammonium hydroxide, an organic solvent, pyrazole and water. When using this cleaning solution, it is possible to suppress damage to a tungsten-containing material, copper or a copper alloy and a titanium-containing material, but a residue cannot be removed, and damage to a low-k film cannot be suppressed. Accordingly, this cleaning solution cannot be used for cleaning a semiconductor element, wherein: damage to a titanium-containing material and a low-k film is suppressed and a dry etching residue is removed; damage to a tungsten-containing material and a low-k film is suppressed and a dry etching residue is removed; or damage to a titanium-containing material, a tungsten-containing material, copper or a copper alloy and a low-k film is suppressed and a dry etching residue is removed, which is the purpose of the present invention (see Comparative Example 41).
Patent Document 19 proposes a wiring forming method using a cleaning solution containing a fluorine compound, a metal corrosion inhibitor, a passivator and water. When using this cleaning solution, it is possible to suppress damage to a tungsten-containing material, copper or a copper alloy and a titanium-containing material, but a residue cannot be removed, and damage to a low-k film cannot be suppressed. Accordingly, this cleaning solution cannot be used for cleaning a semiconductor element, wherein: damage to a titanium-containing material and a low-k film is suppressed and a dry etching residue is removed; damage to a tungsten-containing material and a low-k film is suppressed and a dry etching residue is removed; or damage to a titanium-containing material, a tungsten-containing material, copper or a copper alloy and a low-k film is suppressed and a dry etching residue is removed, which is the purpose of the present invention (see Comparative Example 42).
Patent Document 20 proposes a wiring forming method using a cleaning solution containing ammonium fluoride, gluconic acid and water. When using this cleaning solution, it is possible to suppress damage to a tungsten-containing material, copper or a copper alloy and a titanium-containing material, but a residue cannot be removed, and damage to a low-k film cannot be suppressed. Accordingly, this cleaning solution cannot be used for cleaning a semiconductor element, wherein: damage to a titanium-containing material and a low-k film is suppressed and a dry etching residue is removed; damage to a tungsten-containing material and a low-k film is suppressed and a dry etching residue is removed; or damage to a titanium-containing material, a tungsten-containing material, copper or a copper alloy and a low-k film is suppressed and a dry etching residue is removed, which is the purpose of the present invention (see Comparative Example 43).
Patent Document 21 proposes a wiring forming method using a cleaning solution containing an amine compound, a salt of hydroxylamine, a quaternary ammonium compound, an organic acid, a water-soluble organic solvent and water. When using this cleaning solution, it is possible to suppress damage to a tungsten-containing material and a titanium-containing material, but a residue cannot be removed, and damage to copper or a copper alloy and a low-k film cannot be suppressed. Accordingly, this cleaning solution cannot be used for cleaning a semiconductor element, wherein: damage to a titanium-containing material and a low-k film is suppressed and a dry etching residue is removed; damage to a tungsten-containing material and a low-k film is suppressed and a dry etching residue is removed; or damage to a titanium-containing material, a tungsten-containing material, copper or a copper alloy and a low-k film is suppressed and a dry etching residue is removed, which is the purpose of the present invention (see Comparative Example 44).
Patent Document 22 proposes a wiring forming method using a cleaning solution containing an alkali and WzMXy (in the formula: M represents a metal selected from the group consisting of Si, Ge, Sn, Pt, P, B, Au, Ir, Os, Cr, Ti, Zr, Rh, Ru and Sb; X represents a halide selected from the group consisting of F, Cl, Br and I; W is selected from H, an alkali or alkaline earth metal, and a metal-ion-free hydroxide base moiety; y represents a number of from 4 to 6 depending on a metal halide; and z represents a number of 1, 2 or 3). When using the cleaning solution described in Patent Document 22, it is impossible to remove a dry etching residue, and it is impossible to suppress damage to a tungsten-containing material and a low-k film. Accordingly, this cleaning solution cannot be used for cleaning a semiconductor element, wherein damage to a tungsten-containing material and a low-k film is suppressed and a dry etching residue is removed, which is the purpose of the present invention (see Comparative Example 46). Further, a cleaning solution, in which WzMXy described in the Examples of Patent Document 22 is blended instead of the alkaline earth metal compound that is blended in the cleaning solution of the present invention for the purpose of suppressing damage to the titanium-containing material or the tungsten-containing material, cannot suppress damage to the titanium-containing material and the tungsten-containing material and damages the low-k film (see Comparative Example 47).
Patent Document 23 proposes a method for cleaning a semiconductor substrate using a cleaning solution containing a carbonate and an acidic compound and having a pH value of less than 7.5. Specific examples of the carbonate contained in the cleaning solution include carbonates containing an alkaline earth metal, and it is described that this cleaning solution suppresses corrosion of titanium nitride. However, when using the cleaning solution described in Patent Document 23, it is impossible to remove a dry etching residue, and it is impossible to suppress damage to a titanium-containing material, a tungsten-containing material and copper. Accordingly, this cleaning solution cannot be used for cleaning a semiconductor element, wherein: damage to a titanium-containing material and a low-k film is suppressed and a dry etching residue is removed; damage to a tungsten-containing material and a low-k film is suppressed and a dry etching residue is removed; or damage to a titanium-containing material, a tungsten-containing material, copper or a copper alloy and a low-k film is suppressed and a dry etching residue is removed, which is the purpose of the present invention (see Comparative Example 48). Further, a cleaning solution, in which the carbonate described in the Examples of Patent Document 23 is blended in the cleaning solution of the present invention instead of the alkaline earth metal compound that is blended for the purpose of suppressing damage to the material containing titanium or tungsten, cannot suppress damage to the titanium-containing material and the tungsten-containing material (see Comparative Example 49).